The present disclosure relates to a radio communication device, an oscillation circuit, and a sensitivity suppression reduction method.
A radio communication device typically includes a receiving circuit and an oscillation circuit. The receiving circuit receives a signal wave transmitted from the outside via an antenna, frequency-converts a received RF (Radio Frequency) signal to an IF (Intermediate Frequency) signal, and demodulates the IF signal. The oscillation circuit outputs a local signal for frequency conversion.
The oscillation circuit includes a reference oscillator, and performs PLL (phase-locked loop) control by using a frequency in which the reference oscillator oscillates as a reference frequency. The reference oscillator outputs a reference signal of the reference frequency. The reference oscillator usually generates harmonics of the reference frequency when it oscillates at the reference frequency. The harmonics radiate to a receiving circuit, and interference with the RF signals of the harmonics is a factor causing suppression of the reception sensitivity.
Japanese Unexamined Patent Application Publication No. 2011-14961 (Patent Document 1) discloses that changing the reference frequency reduces the suppression of the reception sensitivity caused by interference of the harmonics.